Hi Laurent, > From: linux-kernel-owner@xxxxxxxxxxxxxxx <linux-kernel-owner@xxxxxxxxxxxxxxx> On Behalf Of Laurent Pinchart > Sent: 05 August 2019 10:36 > Subject: Re: [PATCH/RFC 02/12] dt-bindings: display: renesas: lvds: Document renesas,swap-data > > Hi Fabrizio, > > On Mon, Aug 05, 2019 at 08:59:51AM +0000, Fabrizio Castro wrote: > > > From: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> > > > Sent: 02 August 2019 08:44 > > > Subject: Re: [PATCH/RFC 02/12] dt-bindings: display: renesas: lvds: Document renesas,swap-data > > > > > > Hi Fabrizio, > > > > > > Thank you for the patch. > > > > > > On Fri, Aug 02, 2019 at 08:33:59AM +0100, Fabrizio Castro wrote: > > > > R-Car D3, R-Car E3, and RZ/G2E support dual-link mode. > > > > In such a mode, the first LVDS encoder emits even data, and the > > > > second LVDS encoder emits odd data. This patch documents property > > > > renesas,swap-data, used to swap even and odd data around. > > > > > > > > Signed-off-by: Fabrizio Castro <fabrizio.castro@xxxxxxxxxxxxxx> > > > > --- > > > > Documentation/devicetree/bindings/display/bridge/renesas,lvds.txt | 5 +++++ > > > > 1 file changed, 5 insertions(+) > > > > > > > > diff --git a/Documentation/devicetree/bindings/display/bridge/renesas,lvds.txt > > > b/Documentation/devicetree/bindings/display/bridge/renesas,lvds.txt > > > > index dece79e..8980179 100644 > > > > --- a/Documentation/devicetree/bindings/display/bridge/renesas,lvds.txt > > > > +++ b/Documentation/devicetree/bindings/display/bridge/renesas,lvds.txt > > > > @@ -52,6 +52,11 @@ Optional properties: > > > > mandatory for the first LVDS encoder on R-Car D3, R-Car E3, and RZ/G2E SoCs, > > > > and shall point to the second encoder to be used as a companion in dual-link > > > > mode. It shall not be set for any other LVDS encoder. > > > > +- renesas,swap-data : when in dual-link mode, the first LVDS encoder normally > > > > + emits even data, and the second LVDS encoder emits odd data. When property > > > > + renesas,swap-data is specified, the data emitted by the two encoders will be > > > > + swapped around. This property can only be used in conjunction with property > > > > + renesas,companion. > > > > > > From an LVDS encoder point of view this is more a configuration option > > > than a description of the hardware. Wouldn't it be better for the LVDS > > > sink to report which of the odd or even pixels it expects on each of its > > > endpoints ? > > > > Yes, that would be my preference too, and it would be better, I am just not entirely > > what's the best place for this information though > > > > > The LVDS encoder driver could then query that at runtime and > > > configure itself accordingly. Ideally this should be queried through the > > > drm_bridge_timings structure (or through a similar mean), not through > > > DT. An LVDS sink that has a fixed mapping of odd/even pixels to > > > endpoints wouldn't need the information to be specified in DT at all. > > > > Isn't drm_bridge_timings specific for bridges? > > Its name makes it specific to bridges, but the information it contains > could equally apply to panels. I would thus use it for both, possibly > after renaming it. Will give this a try then. Thanks, Fab > > -- > Regards, > > Laurent Pinchart
